<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script src="../js/jquery-1.11.3.js"></script>
</head>
<body>
<input type="text" value="你好">
<input type="button" value="点我">
<script>
var s = $('input[type=text]').val();
$('input[type=text]').val('我好');



</script>
</body>
</html>